1. Technical Field
The present invention relates to loudspeakers-room environments and, more particularly, a system for objective quantification of listener envelopment of a loudspeakers-room environment.
2. Related Art
The acoustic quality of audio entertainment and audio information systems may depend on the acoustic characteristics of the listening rooms. Such rooms differ in their dimensions and shapes, (e.g., in the range from concert halls to vehicle compartments).
As a sound travels away from its source, a certain proportion of it reaches the listener as direct sound following a straight path. A certain proportion of the sound radiates in all directions from the source and encounters the boundaries of an enclosure. The direct sound and reflections may cause auditory spatial perception. The reflected sound may be delayed and frequency colored. The delay, frequency coloration and reverberation may be captured and interpreted cognitively to give an auditory perception of the sound system and the space in which the sound travels.
Sound reflections may include lateral reflections that are perceived within 1 to 80 ms after the direct sound is received. Late reflections may be perceived more than 80 ms after arrival of a direct sound. The relationship of early lateral reflections with direct sound may provide a person with a sense of the direction and location of the sound source. An auditory source in a room may be perceived as a finite lateral extent. The temporal and spatial separation of sound energy of the late reflection may cause a listener to feel completely enclosed by the sound. This phenomenon is known as the listener envelopment (LEV). The LEV represents the degree of envelopment or fullness of auditory events surrounding the listener.
Derivation and measurement of objective quantifications of the spatial auditory characteristics of a closed listening room are difficult to achieve. Monaural parameters do not often correlate well with perceptible characteristics. Measurement results of binaural parameters may depend on the actual measurement position and are difficult to implement. A ranking of the listener rooms, e.g., concert halls, based on established parameters may not sufficiently match the auditory perception and preferences of human listeners. Therefore, it is difficult to adjust sound-systems including loudspeakers in closed rooms to provide optimum audio quality.